不同层次土壤中微生物群落对扰动和豆科植物生长的响应

发布时间：2018-03-21 10:45

  本文选题：土壤　切入点：根瘤菌　出处：《西北农林科技大学》2017年硕士论文　论文类型：学位论文

【摘要】：微生物在土壤的形成过程中发挥重要作用。然而,不同深度中的土壤微生物对生物和非生物环境扰动的响应过程和多样性变化仍不清楚。本文通过刺槐捕捉试验对杨陵农田土壤0-300cm剖面(0-5、5-10、10-20、20-40、40-60、60-80、80-100、100-120、120-150、150-200、200-250、250-300 cm)12个层次土壤中的根瘤菌分布、系统发育进行了研究,同时对置于花盆中的不同层次的土壤种植刺槐、三叶草以及浇水处理,通过土壤16S rRNA基因高通量测序分析,对扰动后土壤中微生物菌群结构和变化进行了研究。得到如下结果:通过刺槐捕捉试验,从0-300cm土壤剖面中共分离到32株根瘤菌,其中0-100cm土壤分离到的菌株最多(占总数的90.6%)。16S rRNA序列分析表明,这些菌株属于中慢生根瘤菌属(Mesorhizobium)(30株),新根瘤菌属(Neorhizobium)(2株)。持家基因recA-atpD-rpoB串联基因系统发育分析,Mesorhizobium是优势菌(88%),包含一个已知种M.amorphae和三个未定种类群:Mesorhizobium sp.Ⅰ(占68.5%)、Mesorhizobium sp.Ⅱ(占6.25%)、Mesorhizobium sp.Ⅲ(12.5%)。菌株20-40-1和40-60-8与Neorhizobium galegae bv.orientalis HAMBI 540T系统发育关系最近,序列相似性为93.7%。在根瘤菌结瘤基因nodA、固氮基因nifH系统发育分析中,32株根瘤菌与Mesorhizobium聚类成一分支,说明与刺槐共生的根瘤菌的共生基因具有较强专一性。土壤理化在整个土壤剖面中呈现明显的垂直变化,pH值随着土壤深度的增加而增大但变化幅度很小(pH8.21-pH 8.42),土壤有机质、总氮、速效钾和速效磷含量均随土壤深度的增加而降低。与原位土每个层次相比,种植刺槐后土壤中总氮的含量上升,C:N比降低。扰动后土壤16S rRNA高通量测序分析表明,微生物群落的多样性随着土壤深度的增加而降低,也呈现明显的垂直空间分布。土壤理化性质在微生物群落结构组成中起重要作用,变形菌门相对丰度与土壤pH值呈显著负相关,土壤有机质、总氮、有效钾和磷含量对放线菌门、绿弯菌门、浮霉菌门相对丰度影响显著。分析土壤中根瘤菌分布情况发现,根瘤菌目是alpha-变形菌纲的优势菌,其中慢生根瘤菌科和叶瘤菌科相对丰度在扰动后有略微下降,种植刺槐后根瘤菌科相对丰度显著上升。
[Abstract]:Microorganisms play an important role in soil formation. However, The response process and diversity of soil microorganisms to biological and abiotic environmental disturbances in different depths are still unclear. The distribution of rhizobia in 12 soil layers of Yangling farmland was studied in this paper. The distribution of rhizobia in 12 soil layers (0-300cm profile, 0-300cm profile, 5-1010-20C, 20-4040,60,80,80-100m, 100-120-120-1500-200200200-250250-300 cm) soil was studied, and the distribution of rhizobia in 12 soil layers was studied. Phylogeny was studied, and high throughput sequencing of 16s rRNA gene was carried out by planting Robinia pseudoacacia, clover and watering treatments in different layers of soil in flowerpots. The structure and changes of microbial flora in disturbed soil were studied. The following results were obtained: 32 strains of rhizobia were isolated from soil profile of 0-300cm by Robinia pseudoacacia capture test. In 0-100cm soil, the most strains were isolated (90.6%). 16s rRNA sequence analysis showed that, These strains belong to 30 strains of Mesorhizobium, and 2 strains of Neorhizobium. Phylogenetic analysis of recA-atpD-rpoB tandem gene phylogenetic analysis of Mesorhizobium, including a known species M. amorphae and three undetermined species: Mesorhizobium sp. 鈪，

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